fix(user-mgmt): single toast + stable editor on group update (closes #998)

[cristim]

Summary

• Fixes duplicate success toasts when toggling a group checkbox in the User Management expand panel (listener stacking: each renderUsers() call added another document.addEventListener for group-assign-checkbox change events, so N renders produced N toasts per toggle).
• Fixes panel collapsing on first checkbox click: toggleUserGroup previously called loadUsers() which called renderUsers() which replaced the whole table innerHTML, resetting all expand rows to hidden.
• Fixes the first-click-unresponsive-after-collapse symptom, which was a downstream effect of the same re-render teardown.

Root cause

setupUserTableListeners() (called by renderUsers()) registered the group-assign handler with a bare document.addEventListener. No cleanup. Every re-render stacked another listener, so after N group saves the N-th toast fired N times.

toggleUserGroup called loadUsers() on success which called renderUsers() which nuked the DOM and collapsed the panel before the user could make a second group change.

Fix

• Added a module-level AbortController (groupAssignListenerCtrl). Each setupUserTableListeners() call aborts the previous controller and creates a fresh one, so only one listener is ever active. Same pattern as settings.ts:1564-1565.
• toggleUserGroup no longer calls loadUsers(). Instead: patch the user in allUsers in-memory, then re-render only the affected expand panel (panel.innerHTML = renderUserExpandPanel(updatedUser)) and the groups-cell badge in the main row. The expand row stays open; the user can make multiple group changes without the panel collapsing.

Test plan

8 new tests added to users.test.ts under group assignment UX (issue #998):

• Single toggle emits exactly one success toast
• Three renderUsers() calls before a toggle still emit exactly one toast (direct regression test for listener stacking)
• Expand row is NOT hidden after a group toggle
• Expand panel element stays in the DOM after a toggle
• Expand button opens panel on first click after renderUsers
• Expand button toggles correctly after multiple renderUsers calls
• allUsers state reflects added group after toggle
• allUsers state reflects removed group after toggle

All 204 users tests pass; full 71-suite frontend test run green; tsc --noEmit clean; npm run build succeeds.

closes #998

Summary by CodeRabbit

• Bug Fixes

  • Fixed group assignment to patch user state in-memory and update only affected UI elements instead of reloading the entire user list.
  • Prevented duplicate toast notifications from stacking listeners during group assignment operations.

• Tests

  • Added comprehensive tests for group assignment functionality, verifying panel persistence and listener behavior.

[cristim]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 879f7b2c-dad8-4576-a380-8ab5a62fbb30

📥 Commits

Reviewing files that changed from the base of the PR and between 5f037eb and 0c8d1d2.

📒 Files selected for processing (2)

• frontend/src/__tests__/users.test.ts
• frontend/src/users/userList.ts

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📝 Walkthrough

Walkthrough

This PR fixes issue #998 by preventing duplicate event listeners and avoiding panel collapse during group edits. An AbortController replaces stacked change listeners on each render, eliminating duplicate toasts. In toggleUserGroup, full-user reload is replaced with targeted in-memory state patching and localized UI updates, keeping the expanded panel open during editing.

Changes

Group Assignment UX Fix

Layer / File(s)	Summary
Event listener deduplication with AbortController frontend/src/users/userList.ts	Module-level groupAssignListenerCtrl AbortController is initialized and used to abort prior document-level change listeners before attaching new ones, preventing listener accumulation and duplicate toast emissions on each renderUsers() call.
In-place state and UI patching for group toggles frontend/src/users/userList.ts	toggleUserGroup documentation and implementation revised to patch userState.allUsers in-memory, re-render the expand panel contents and groups cell inline, and show a single success toast instead of reloading all users, eliminating panel collapse during group edits.
Comprehensive UI behavior tests for group assignment frontend/src/__tests__/users.test.ts	New test suite validates single-toast emission across repeated renders, expand-panel persistence after toggles, expand-button listener reliability, and in-memory group state synchronization.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A rabbit's cheer for deeds so fine—
One toast, not many, in line!
The panel stays put, no collapse in sight,
The checkbox dance flows smooth and right! ✨

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/998-group-update-ux

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[cristim]

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